WAVE-THEORY OF MATTER 203 



verifying this prediction. I scarcely know whether they 

 are yet to be considered conclusive, but there does seem 

 to be serious evidence that in the scattering of electrons 

 by atoms phenomena occur which would not be pro- 

 duced according to the usual theory that electrons are 

 purely corpuscular. These effects analogous to the 

 diffraction and interference of light carry us into the 

 stronghold of the wave-theory. Long ago such phe- 

 nomena ruled out all purely corpuscular theories of 

 light; perhaps to-day we are finding similar phenomena 

 which will rule out all purely corpuscular theories of 

 matter.* 



A similar idea was entertained in a "new statistical 

 mechanics" developed by Einstein and Bose — at least 

 that seems to be the physical interpretation of the highly 

 abstract mathematics of their theory. As so often hap- 

 pens the change from the classical mechanics, though 

 far-reaching in principle, gave only insignificant cor- 

 rections when applied to ordinary practical problems. 

 Significant differences could only be expected in matter 

 much denser than anything yet discovered or imagined. 

 Strange to say, just about the time when it was realised 

 that very dense matter might have strange properties 

 different from those expected according to classical 

 conceptions, very dense matter was found in the uni- 

 verse. Astronomical evidence seems to leave practically 

 no doubt that in the so-called white dwarf stars the 

 density of matter far transcends anything of which we 

 have terrestrial experience; in the Companion of Sirius, 

 for example, the density is about a ton to the cubic inch. 

 This condition is explained by the fact that the high 

 temperature and correspondingly intense agitation of 



*The evidence is much stronger now than when the lectures were 

 delivered. 



